Persistence of IPv4 security model threatens open Net: ISOC

Director of the DO Hub Program for the Internet Society (ISOC), Richard Jimmerson

New IPv6 protocols may allow telecommunications carriers to step away from the idiosyncrasies of Network Address Translation (NAT), but the need to provide legacy IPv4 and NAT support could see them locking customers into IPv4 'walled gardens' that threaten the open nature of the Internet.

That was the warning from Richard Jimmerson, director of the Internet Society (ISOC) of Australia's DO Hub initiative and a key figure within the promotion of IPv6 in Australia, to attendees at this week's IPv6 Summit in Melbourne. Although telcos are keen to embrace IPv6, Jimmerson said, the industry is currently in a long transition phase and they still need to provide a seamless customer experience by supporting connected devices designed for the NAT-based IPv4 world.

IPv6 offers a flatter and less complicated peer-to-peer environment that incorporates built-in IPSec security rather than relying on large-scale NAT (LSN), a high-end NAT that intermediates between systems on a network and the Internet at large. It's a big step forward – but even as the Internet slowly moves to support IPv6, ISPs are likely to instead end up with LSNs that isolate users in tightly controlled IPv4 environments.

This isolation, Jimmerson warned, could become disastrous. Large numbers of users in such a configuration would miss out on the improved security and peer-to-peer connectivity of IPv6, leaving them open to IPv4-based security attacks while confounding common NAT-averse network applications compromising security procedures such as IP address logging.

Over time, telcos will face a difficult choice: content providers, keen to get their content to the large numbers of customers behind an LSN may pursue exclusive deals with ISPs that would create ghettos of IPv4 users. This may go against efforts to help steer the whole Internet towards IPv6, but Jimmerson believes telcos may find it hard to pass up the opportunity.

"I don't think large ISPs and telecoms companies are evil today," Jimmerson said, "but once they find themselves [being courted by content providers] it's going to be really hard to resist because all of a sudden they're going to get paid for services again. If we stick with IPv4, that's exactly where we're going. The permission-free Internet, which we enjoy today and is free and open to everyone, is at severe risk if we do not deploy IPv6."

Carriers face a problem, however: most of those that are deploying IPv6 are now doing so using 'dual-stack' approaches that combine IPv4 and IPv6 support and complicate security profiles by forcing IT staff to straddle both technologies. "They have no choice," Jimmerson said. "It's too late to just cut over from v4 to v6. That boat sailed a long time ago. But the risk is that the industry gets too comfortable with an IPv4 LSN."

Yet not everybody agreed with Jimmerson's threat assessment. Tony Hain, principal of Hain Global Consulting and a previous co-chair of the IETF standards group developing IPv6 transition tools, pointed out that NAT isn't as much of an obstacle as it was in the past, when address translation interfered with security protocols and general communications between local subnets and the Internet. NAT-aware protocols like BitTorrent, for example, are able to traverse from the public Internet onto CGN-isolated subnets without getting blocked along the way.

"BitTorrent doesn't care about walled gardens," Hain said in a talk tracing the way that the transition from protocols like AppleTalk and SNA to TCP/IP had had been eased by encapsulating the legacy protocol inside 'tunnels' built using the new protocol. In a similar way, carriers could encapsulate IPv4 traffic inside IPv6 packets and push users towards all-IPv6 cores that aren't reliant on legacy CGN setups.

Increasingly intelligent protocols could use this approach to bypass the CGN's controls, he offered: "Sure, we have this threat of evil telcos taking control, but they can only do so much," he said. "The Internet got built over the top of all those evil telcos that were saying their networks were only for voice – and protocol evolution is a part of life. The real question is how to raise the pain level to get people off of IPv4 and onto the devices they want."

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